Throttle-shutoff valve

ABSTRACT

The valve includes both a bevelled plug, which cooperates with a seat assembly to throttle flow, and an annular, flat seating surface surrounding the plug, which seats against a corresponding annular, flat seating surface on the seat assembly when the valve is fully closed. The seating surfaces are made from a hardened material having a Brinell hardness greater than 500 so that the valve is capable of being used to control the flow of hightemperature, high-pressure fluids, such as steam. The hardness of one seating surface is greater than that of the other to minimize galling and the seating surfaces are positioned away from the direct eroding effect of the high velocity flow during throttling, thereby maximizing valve life. The valve and seat assembly can be easily removed for renewal of the flat seating surfaces by relapping or the like.

United States Patent [1 1 Robinson Oct. 23, 1973 THROTTLE-SHUTOFF VALVEBernie E. Robinson, Oak Creek,

Wis.

Assignee: Milwaukee Valve Company, Inc.,,

Milwaukee, Wis.

Filed: July 1, 1971 Appl. No.: 158,737

Inventor:

[52] U.S. Cl. 251/122, 251/368 [51] Int. Cl. Fl6k 25/04, F161: 47/04[58] Field of Search 251/122, 210, 368, 251/121 [56] References CitedUNITED STATES PATENTS 1,991,052 2/1935 Derby 251/121 3,219,311 11/1965Siver 251/210 X 2,301,355 11/1942 Armentrout. 251/360 X 1,929,97310/1933 Haley 251/122 X 3,391,901 7/1968 Witeelen et a1 251/368 X3,160,391 12/1964 Medicus et al. 251/368 X OTHER PUBLICATIONS 1971Materials Engineering; Materials Selector Issue;

Mid-November, 1970; pages 71 and 72 Primary Examiner-Arnold RosenthalAttorneyJohn W. Michael et a1.

[57] ABSTRACT The valve includes both a bevelled plug, which cooperateswith a seat assembly to throttle flow, and an annular, flat seatingsurface surrounding the plug, which seats against a correspondingannular, flat seating surface on the seat assembly when the valve isfully closed. The seating surfaces are made from a hardened materialhaving a Brinell hardness greater than 500 so that the valve is capableof being used to control the flow of high-temperature, high-pressurefluids, such as steam. The hardness of one seating surface is greaterthan that of the other to minimize galling and the'seating surfaces arepositioned away from the direct eroding effect of the high velocity flowduring throttling, thereby maximizing valve life. The valve and seatassembly can be easily removed for renewal of the flat seating surfacesby relapping or the like.

4 Claims, 2 Drawing Figures lil 7 Patented Oct. 23,1973

Jae/02502 THROTTLE-SHUTOFF VALVE BACKGROUND OF THE INVENTION Valves usedfor throttling fluid flow typically employ a bevelled plug whichcooperates with an annular seat to meter the flow. Fluid flow is shutoff when the bevelled section of the plug engages the seat. Valves ofthis type provide accurate throttling; however, when used in severeservice (such as in high pressure steam systems), wear of the seat andplug from the eroding effect of the high velocity flow often causesleakage. The seat and/or plug can be removed and the seating surfacesrefinished; however, this remedial action does not always eliminate theleakage problem because the small sealing area between plug and seatrequires very precise tolerances to obtain complete sealing. Hence,components of the valve or the complete valve assembly frequently mustbe replaced. In order to alleviate the problem, it becomes necessary inmany systems to employ a separate shutoff valve, acting as a back-upshutoff, which has a relatively wide, flat seat and flat disc. Thelarger seating area between the seat and the disc provide a greatersealing area and the flat surfaces can be more easily relapped toreinstate the sealing provided thereby. However, shutoff valves of thistype do not provide accurate throttling and cannot be used as a throttlevalve where accurate control of the flow rate of the fluid is required.Where both shutoff and throttle valves are used, users must maintain aninventory of both types of valves.

SUMMARY OF THE INVENTION The throttle-shutoff valve described in theAbstract can be used in severe fluid service, such as high pressuresteam, and can function as a shutoff valve as well as a throttle valve.This dual capability eliminates the necessity of using separate throttleand shutoff valves to obtain accurate flow control and reliable,leak-free fluid shutoff. Also, this dual capability permits the valve tobe used interchangeably with either conventional throttle valves orshutoff valves thereby minimizing inventory requirements for the user.The use of materials having a high Brinell hardness for the seatingsurfaces with a differential hardness between the two,

and arranging these surfaces out of the direct flow of BRIEF DESCRIPTIONOF THE DRAWINGS FIG. 1 is a side elevation, partially sectioned, view ofthe throttle-shutoff valve showing the valve in the closed position.

FIG. 2 is a fragmentary view, partially sectioned, showing the valvepartially open in a throttling position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Valve body 10 includes an inlet12 and an outlet 14 separated by partition 16 into which annular valveseat assembly 18 is threaded. Valve 20 cooperates with seat assembly 18to control the flow of a high pressure, high temperature fluid (e.g.steam) from inlet 12 to outlet 14 through aperture 22 of the seatassembly. Valve 20 is carried by a stem 24, the lower flanged end 26 ofwhich fits into slotted, undercut recess 28 in the valve. The upperportion of the stem 24 (not shown) is threaded into valve bonnet 30 sothat rotation of hand wheel 32, connected to the top of the stem, movesthe stem up and down to control the position of valve 20.

Valve seat assembly 18 has a raised, annular, flat seating surface 34,which seats with a corresponding, raised, annular flat seating surface36 on valve 20 and shuts off fluid flow when the valve is in the closedposition as shown in FIG. 1. Both the seating surfaces are made from ahardened metal, such as stainless steel, having a Brinell hardnessgreater than 500, preferably greater than 550. With this high hardness,the valve can be used for long periods in extremely severe servicewithout significant wear to the seating surfaces and, therefore, withoutleakage. The two seating surfaces have a different Brinell hardnesswhich minimizes galling and further increases their effective life.Preferably, the seating surface 36 on the valve has the higher Brinellhardness. This difference in Brinell hardness is usually at least 10 andpreferably about 50 or higher. For example, the Brinell hardness ofseating surface 34 can be about 550 and seating surface 36 about 600.

Valve seat assembly 18 includes small notches 38 and flat surfaces 40 atthe lower end of the inside wall of aperture 22 which are arranged toaccommodate a wrench or similar tool so that the assembly can be easilyremoved from the body for relapping seating surface 34. Also, valve 20can be removed for relapping seating surface 36 by simply looseningbonnet nut 43 (which holds bonnet 32 to valve body 10), separating thebonnet from the valve body and slipping the valve off stem 24. Hence,the flat seating surfaces of the valve and seat assembly are readilyaccessible for renewal by relapping in the event leakage develops.

When the valve is partially opened as shown in FIG. 2, fluid flowthrough aperture 22 is throttled by plug section 42 of valve 20. Theflow is metered through the area defined between the bevelled section 44of plug 42 and the inside wall of aperture 22. This metering area variesdependent upon the position of valve 20. Seating surfaces 34 and 36 arenot directly exposed to the high velocity fluid flowing through themetering area when the valve is in a throttling position. Therefore,surface wear is reduced and the effective sealing life of these surfacesis increased. Cavity 46, valve body 10 and stem 24 are arranged so thatthe valve can be raised completely away from seat assembly 18 so thatthe plug does not throttle flow and there is full fluid flow throughaperture 22.

From the above detailed description, it can be seen that the valve'ofthis invention is capable of either accurately controlling the flow rateof a hightemperature, high-pressure fluid or acting as a shutoff valvewhich provides full flow when completely open. Since the valve can beused either as a shutoff valve or a throttle valve, users need only keepone type of valve in inventory rather than separate ones for eachpurpose. The ability of the flat seating surfaces of the seat assemblyand valve to be renewed by relapping allows tion;

a seat assembly carried by said partition, said seat assembly includinga central aperture having an inner ing ring surrounding said plugsection and adapted to engage said seat assembly seating ring andcooperate therewith to provide a fluid tight seal when said valve memberis in a closed position, said seat wall defining a generally cylindricalflow passage 5 assembly and valve member seating rings beingcommunicating with said inlet and outlet and furmade from a metallicmaterial having a Brinell ther including an annular, renewable,flat-surfaced hardness greater than 500 with the Brinell hardnessseating ring surrounding said aperture; of one differing from that ofthe other by at least valve member adapted for reciprocal movement andwithin said body relative to said seat assembly be- 10 means foradjustably moving said valve member between an open position where thereis substantially unrestricted flow through said flow passage and a tweenthe open and closed position. 2. The valve according to claim 1 whereinthe Brinell hardness of said valve member seating ring is at least 10greater than that of said seating assembly seating ring. 3. The valveaccording to claim 2 wherein the Brinell hardness of said valve memberseating ring is at least 550.

4. The valve according to claim 1 wherein said seat assembly isremovably mounted in said partition.

closed position to shut off flow through said flow passage, said valvemember including a beveled plug section adapted to extend into said flowpassage without seating against said aperture and to cooperate with saidaperture, as said valve member is moved from and towards the closedposition, to vary the flow through said flow passage and furtherincluding an annular, renewable, flat-surfaced seat-

1. A valve comprising a body having an inlet and outlet separated by apartition; a seat assembly carried by said partition, said seat assemblyincluding a central aperture having an inner wall defining a generallycylindrical flow passage communicating with said inlet and outlet andfurther including an annular, renewable, flat-surfaced seating ringsurrounding said aperture; a valve member adapted for reciprocalmovement within said body relative to said seat assembly between an openposition where there is substantially unrestricted flow through saidflow passage and a closed position to shut off flow through said flowpassage, said valve member including a beveled plug section adapted toextend into said flow passage without seating against said aperture andto cooperate with said aperture, as said valve member is moved from andtowards the closed position, to vary the flow through said flow passageand further including an annular, renewable, flat-surfaced seating ringsurrounding said plug section and adapted to engage said seat assemblyseating ring and cooperate therewith to provide a fluid tight seal whensaid valve member is in a closed position, said seat assembly and valvemember seating rings being made from a metallic material having aBrinell hardness greater than 500 with the Brinell hardness of onediffering from that of the other by at least 10; and means foradjustably moving said valve member between the open and closedposition.
 2. The valve according to claim 1 wherein the Brinell hardnessof said valve member seating ring is at least 10 greater than that ofsaid seating assembly seating ring.
 3. The valve according to claim 2wherein the Brinell hardness of said valve member seating ring is atleast
 550. 4. The valve according to claim 1 wherein said seat assemblyis removably mounted in said partition.